Fueled by advances in basic research with HIV, a number of new approaches for prevention and treatment of AIDS are emerging. These either are or soon will be in clinical trials and the 1994 Keystone Conference on AIDS should provide and opportunity to review various features of these studies. It can be anticipated, for instance, that clinical evaluation of new antivirals such as inhibitors of the tat gene product and of the viral protease will have progressed to a point where meaningful comparisons to other treatment modalities can be made. Other therapeutic approaches such as inhibitors of viral activators such as TNF and various gene therapy trials may also be underway. Several immune based therapies such as post- exposure immunization with various viral vaccine preparations should be at point where potential benefits to the patient can be evaluated. Passive immunotherapy with various antibodies or adoptive immunotherapy with cells will also be undergoing clinical evaluation. One setting of particular interest where drugs, as well as active and passive immunization approaches will be studied is in prevention of HIV transmission from mother to infant. Preventive vaccines will be at a crossroads as the infrastructures for conducting efficacy trials are being established. However, all important decisions of how vaccines will be selected for entry into such trials are questions that are still open and will receive attention at this meeting. Complementing these pragmatic issues will be a review of the latest advances in basic research with HIV, which has always been a cornerstone of the multidisciplinary Keystone Conferences on AIDS. The topics that will be featured in 1994 will include: 1) virus/cell interactions (mechanisms of viral entry, viral tropism, regulation of gene expression and pathogenesis); 2) new insights on HIV transmission; 3) the extent and significance of virus variation; 4) humoral and cellular responses to HIV; and 5) new models for HIV infection and disease.